/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */
package io.netty.buffer;

import static io.netty.util.internal.ObjectUtil.checkPositiveOrZero;

import io.netty.util.internal.PlatformDependent;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.channels.ClosedChannelException;
import java.nio.channels.FileChannel;
import java.nio.channels.GatheringByteChannel;
import java.nio.channels.ScatteringByteChannel;

/**
 * A NIO {@link ByteBuffer} based buffer. It is recommended to use {@link
 * UnpooledByteBufAllocator#directBuffer(int, int)}, {@link Unpooled#directBuffer(int)} and {@link
 * Unpooled#wrappedBuffer(ByteBuffer)} instead of calling the constructor explicitly.}
 */
public class UnpooledUnsafeDirectByteBuf extends AbstractReferenceCountedByteBuf {

  private final ByteBufAllocator alloc;

  private ByteBuffer tmpNioBuf;
  private int capacity;
  private boolean doNotFree;
  ByteBuffer buffer;
  long memoryAddress;

  /**
   * Creates a new direct buffer.
   *
   * @param initialCapacity the initial capacity of the underlying direct buffer
   * @param maxCapacity the maximum capacity of the underlying direct buffer
   */
  public UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, int initialCapacity, int maxCapacity) {
    super(maxCapacity);
    if (alloc == null) {
      throw new NullPointerException("alloc");
    }
    checkPositiveOrZero(initialCapacity, "initialCapacity");
    checkPositiveOrZero(maxCapacity, "maxCapacity");
    if (initialCapacity > maxCapacity) {
      throw new IllegalArgumentException(String.format(
          "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
    }

    this.alloc = alloc;
    setByteBuffer(allocateDirect(initialCapacity), false);
  }

  /**
   * Creates a new direct buffer by wrapping the specified initial buffer.
   *
   * @param maxCapacity the maximum capacity of the underlying direct buffer
   */
  protected UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer,
      int maxCapacity) {
    // We never try to free the buffer if it was provided by the end-user as we not know if this is an duplicate or
    // an slice. This is done to prevent an IllegalArgumentException when using Java9 as Unsafe.invokeCleaner(...)
    // will check if the given buffer is either an duplicate or slice and in this case throw an
    // IllegalArgumentException.
    //
    // See http://hg.openjdk.java.net/jdk9/hs-demo/jdk/file/0d2ab72ba600/src/jdk.unsupported/share/classes/
    // sun/misc/Unsafe.java#l1250
    //
    // We also call slice() explicitly here to preserve behaviour with previous netty releases.
    this(alloc, initialBuffer.slice(), maxCapacity, false);
  }

  UnpooledUnsafeDirectByteBuf(ByteBufAllocator alloc, ByteBuffer initialBuffer, int maxCapacity,
      boolean doFree) {
    super(maxCapacity);
    if (alloc == null) {
      throw new NullPointerException("alloc");
    }
    if (initialBuffer == null) {
      throw new NullPointerException("initialBuffer");
    }
    if (!initialBuffer.isDirect()) {
      throw new IllegalArgumentException("initialBuffer is not a direct buffer.");
    }
    if (initialBuffer.isReadOnly()) {
      throw new IllegalArgumentException("initialBuffer is a read-only buffer.");
    }

    int initialCapacity = initialBuffer.remaining();
    if (initialCapacity > maxCapacity) {
      throw new IllegalArgumentException(String.format(
          "initialCapacity(%d) > maxCapacity(%d)", initialCapacity, maxCapacity));
    }

    this.alloc = alloc;
    doNotFree = !doFree;
    setByteBuffer(initialBuffer.order(ByteOrder.BIG_ENDIAN), false);
    writerIndex(initialCapacity);
  }

  /**
   * Allocate a new direct {@link ByteBuffer} with the given initialCapacity.
   */
  protected ByteBuffer allocateDirect(int initialCapacity) {
    return ByteBuffer.allocateDirect(initialCapacity);
  }

  /**
   * Free a direct {@link ByteBuffer}
   */
  protected void freeDirect(ByteBuffer buffer) {
    PlatformDependent.freeDirectBuffer(buffer);
  }

  final void setByteBuffer(ByteBuffer buffer, boolean tryFree) {
    if (tryFree) {
      ByteBuffer oldBuffer = this.buffer;
      if (oldBuffer != null) {
        if (doNotFree) {
          doNotFree = false;
        } else {
          freeDirect(oldBuffer);
        }
      }
    }
    this.buffer = buffer;
    memoryAddress = PlatformDependent.directBufferAddress(buffer);
    tmpNioBuf = null;
    capacity = buffer.remaining();
  }

  @Override
  public boolean isDirect() {
    return true;
  }

  @Override
  public int capacity() {
    return capacity;
  }

  @Override
  public ByteBuf capacity(int newCapacity) {
    checkNewCapacity(newCapacity);

    int readerIndex = readerIndex();
    int writerIndex = writerIndex();

    int oldCapacity = capacity;
    if (newCapacity > oldCapacity) {
      ByteBuffer oldBuffer = buffer;
      ByteBuffer newBuffer = allocateDirect(newCapacity);
      oldBuffer.position(0).limit(oldBuffer.capacity());
      newBuffer.position(0).limit(oldBuffer.capacity());
      newBuffer.put(oldBuffer);
      newBuffer.clear();
      setByteBuffer(newBuffer, true);
    } else if (newCapacity < oldCapacity) {
      ByteBuffer oldBuffer = buffer;
      ByteBuffer newBuffer = allocateDirect(newCapacity);
      if (readerIndex < newCapacity) {
        if (writerIndex > newCapacity) {
          writerIndex(writerIndex = newCapacity);
        }
        oldBuffer.position(readerIndex).limit(writerIndex);
        newBuffer.position(readerIndex).limit(writerIndex);
        newBuffer.put(oldBuffer);
        newBuffer.clear();
      } else {
        setIndex(newCapacity, newCapacity);
      }
      setByteBuffer(newBuffer, true);
    }
    return this;
  }

  @Override
  public ByteBufAllocator alloc() {
    return alloc;
  }

  @Override
  public ByteOrder order() {
    return ByteOrder.BIG_ENDIAN;
  }

  @Override
  public boolean hasArray() {
    return false;
  }

  @Override
  public byte[] array() {
    throw new UnsupportedOperationException("direct buffer");
  }

  @Override
  public int arrayOffset() {
    throw new UnsupportedOperationException("direct buffer");
  }

  @Override
  public boolean hasMemoryAddress() {
    return true;
  }

  @Override
  public long memoryAddress() {
    ensureAccessible();
    return memoryAddress;
  }

  @Override
  protected byte _getByte(int index) {
    return UnsafeByteBufUtil.getByte(addr(index));
  }

  @Override
  protected short _getShort(int index) {
    return UnsafeByteBufUtil.getShort(addr(index));
  }

  @Override
  protected short _getShortLE(int index) {
    return UnsafeByteBufUtil.getShortLE(addr(index));
  }

  @Override
  protected int _getUnsignedMedium(int index) {
    return UnsafeByteBufUtil.getUnsignedMedium(addr(index));
  }

  @Override
  protected int _getUnsignedMediumLE(int index) {
    return UnsafeByteBufUtil.getUnsignedMediumLE(addr(index));
  }

  @Override
  protected int _getInt(int index) {
    return UnsafeByteBufUtil.getInt(addr(index));
  }

  @Override
  protected int _getIntLE(int index) {
    return UnsafeByteBufUtil.getIntLE(addr(index));
  }

  @Override
  protected long _getLong(int index) {
    return UnsafeByteBufUtil.getLong(addr(index));
  }

  @Override
  protected long _getLongLE(int index) {
    return UnsafeByteBufUtil.getLongLE(addr(index));
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuf dst, int dstIndex, int length) {
    UnsafeByteBufUtil.getBytes(this, addr(index), index, dst, dstIndex, length);
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, byte[] dst, int dstIndex, int length) {
    UnsafeByteBufUtil.getBytes(this, addr(index), index, dst, dstIndex, length);
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, ByteBuffer dst) {
    UnsafeByteBufUtil.getBytes(this, addr(index), index, dst);
    return this;
  }

  @Override
  public ByteBuf readBytes(ByteBuffer dst) {
    int length = dst.remaining();
    checkReadableBytes(length);
    getBytes(readerIndex, dst);
    readerIndex += length;
    return this;
  }

  @Override
  protected void _setByte(int index, int value) {
    UnsafeByteBufUtil.setByte(addr(index), value);
  }

  @Override
  protected void _setShort(int index, int value) {
    UnsafeByteBufUtil.setShort(addr(index), value);
  }

  @Override
  protected void _setShortLE(int index, int value) {
    UnsafeByteBufUtil.setShortLE(addr(index), value);
  }

  @Override
  protected void _setMedium(int index, int value) {
    UnsafeByteBufUtil.setMedium(addr(index), value);
  }

  @Override
  protected void _setMediumLE(int index, int value) {
    UnsafeByteBufUtil.setMediumLE(addr(index), value);
  }

  @Override
  protected void _setInt(int index, int value) {
    UnsafeByteBufUtil.setInt(addr(index), value);
  }

  @Override
  protected void _setIntLE(int index, int value) {
    UnsafeByteBufUtil.setIntLE(addr(index), value);
  }

  @Override
  protected void _setLong(int index, long value) {
    UnsafeByteBufUtil.setLong(addr(index), value);
  }

  @Override
  protected void _setLongLE(int index, long value) {
    UnsafeByteBufUtil.setLongLE(addr(index), value);
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuf src, int srcIndex, int length) {
    UnsafeByteBufUtil.setBytes(this, addr(index), index, src, srcIndex, length);
    return this;
  }

  @Override
  public ByteBuf setBytes(int index, byte[] src, int srcIndex, int length) {
    UnsafeByteBufUtil.setBytes(this, addr(index), index, src, srcIndex, length);
    return this;
  }

  @Override
  public ByteBuf setBytes(int index, ByteBuffer src) {
    UnsafeByteBufUtil.setBytes(this, addr(index), index, src);
    return this;
  }

  @Override
  public ByteBuf getBytes(int index, OutputStream out, int length) throws IOException {
    UnsafeByteBufUtil.getBytes(this, addr(index), index, out, length);
    return this;
  }

  @Override
  public int getBytes(int index, GatheringByteChannel out, int length) throws IOException {
    return getBytes(index, out, length, false);
  }

  private int getBytes(int index, GatheringByteChannel out, int length, boolean internal)
      throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf;
    if (internal) {
      tmpBuf = internalNioBuffer();
    } else {
      tmpBuf = buffer.duplicate();
    }
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf);
  }

  @Override
  public int getBytes(int index, FileChannel out, long position, int length) throws IOException {
    return getBytes(index, out, position, length, false);
  }

  private int getBytes(int index, FileChannel out, long position, int length, boolean internal)
      throws IOException {
    ensureAccessible();
    if (length == 0) {
      return 0;
    }

    ByteBuffer tmpBuf = internal ? internalNioBuffer() : buffer.duplicate();
    tmpBuf.clear().position(index).limit(index + length);
    return out.write(tmpBuf, position);
  }

  @Override
  public int readBytes(GatheringByteChannel out, int length) throws IOException {
    checkReadableBytes(length);
    int readBytes = getBytes(readerIndex, out, length, true);
    readerIndex += readBytes;
    return readBytes;
  }

  @Override
  public int readBytes(FileChannel out, long position, int length) throws IOException {
    checkReadableBytes(length);
    int readBytes = getBytes(readerIndex, out, position, length, true);
    readerIndex += readBytes;
    return readBytes;
  }

  @Override
  public int setBytes(int index, InputStream in, int length) throws IOException {
    return UnsafeByteBufUtil.setBytes(this, addr(index), index, in, length);
  }

  @Override
  public int setBytes(int index, ScatteringByteChannel in, int length) throws IOException {
    ensureAccessible();
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    try {
      return in.read(tmpBuf);
    } catch (ClosedChannelException ignored) {
      return -1;
    }
  }

  @Override
  public int setBytes(int index, FileChannel in, long position, int length) throws IOException {
    ensureAccessible();
    ByteBuffer tmpBuf = internalNioBuffer();
    tmpBuf.clear().position(index).limit(index + length);
    try {
      return in.read(tmpBuf, position);
    } catch (ClosedChannelException ignored) {
      return -1;
    }
  }

  @Override
  public int nioBufferCount() {
    return 1;
  }

  @Override
  public ByteBuffer[] nioBuffers(int index, int length) {
    return new ByteBuffer[]{nioBuffer(index, length)};
  }

  @Override
  public ByteBuf copy(int index, int length) {
    return UnsafeByteBufUtil.copy(this, addr(index), index, length);
  }

  @Override
  public ByteBuffer internalNioBuffer(int index, int length) {
    checkIndex(index, length);
    return (ByteBuffer) internalNioBuffer().clear().position(index).limit(index + length);
  }

  private ByteBuffer internalNioBuffer() {
    ByteBuffer tmpNioBuf = this.tmpNioBuf;
    if (tmpNioBuf == null) {
      this.tmpNioBuf = tmpNioBuf = buffer.duplicate();
    }
    return tmpNioBuf;
  }

  @Override
  public ByteBuffer nioBuffer(int index, int length) {
    checkIndex(index, length);
    return ((ByteBuffer) buffer.duplicate().position(index).limit(index + length)).slice();
  }

  @Override
  protected void deallocate() {
    ByteBuffer buffer = this.buffer;
    if (buffer == null) {
      return;
    }

    this.buffer = null;

    if (!doNotFree) {
      freeDirect(buffer);
    }
  }

  @Override
  public ByteBuf unwrap() {
    return null;
  }

  long addr(int index) {
    return memoryAddress + index;
  }

  @Override
  protected SwappedByteBuf newSwappedByteBuf() {
    if (PlatformDependent.isUnaligned()) {
      // Only use if unaligned access is supported otherwise there is no gain.
      return new UnsafeDirectSwappedByteBuf(this);
    }
    return super.newSwappedByteBuf();
  }

  @Override
  public ByteBuf setZero(int index, int length) {
    checkIndex(index, length);
    UnsafeByteBufUtil.setZero(addr(index), length);
    return this;
  }

  @Override
  public ByteBuf writeZero(int length) {
    ensureWritable(length);
    int wIndex = writerIndex;
    UnsafeByteBufUtil.setZero(addr(wIndex), length);
    writerIndex = wIndex + length;
    return this;
  }
}
